Application: gvSIG desktop

package org.gvsig.expressionevaluator.impl.function.programming;

import java.util.Objects;

import org.apache.commons.lang3.Range;

import org.gvsig.expressionevaluator.Code;

import org.gvsig.expressionevaluator.Codes;

import org.gvsig.expressionevaluator.ExpressionBuilder;

import org.gvsig.expressionevaluator.Formatter;

import org.gvsig.expressionevaluator.Function;

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.MutableSymbolTable;

import org.gvsig.expressionevaluator.SymbolTable;

import org.gvsig.expressionevaluator.spi.AbstractFunction;

public class VarFunction extends AbstractFunction {

    public static final String NAME="VAR";

    public VarFunction() {

        super(Function.GROUP_PROGRAMMING, 

                NAME, 

            Range.between(1,2),

            "Declare a variable.\nExample:\n  VAR x DEFAULT 0\n",

            NAME+" {{identifier}} DEFAULT default_value",

            new String[]{

                "identifier_name - Name of the variable",

                "default_value - Value to assign to the variable if have to create it."

            },

            "NULL",

            false

        );

    }

    @Override

    public boolean allowConstantFolding() {

        return false;

    }

    @Override

    public Object call(Interpreter interpreter, Object[] args) throws Exception {

//        String name = getStr(args,0);

//        if( name == null ) {

//            throw new NullPointerException("A string with a variable name was expected and a null was received");

//        }

//        Object value = null;

//        if( args.length==2 ) {

//            value = getObject(args, 1);

//        }

//        SymbolTable symbolTable = interpreter.getSymbolTable();

//        if( symbolTable instanceof MutableSymbolTable ) {

//            if( !symbolTable.exists(name)) {

//                ((MutableSymbolTable)symbolTable).setVar(name, value);

//            }

//        } else {

//            throw new RuntimeException("A MutableSymbolTable is required for use VAR function.");

//        }

        return null;

    }

    @Override

    public Object call(Interpreter interpreter, Codes args) throws Exception {

        Code varNameCode = args.get(0);

        if(varNameCode.code() != Code.IDENTIFIER){

            throw new RuntimeException("First argument must be a identifier.");

        }

        String name = ((Code.Identifier)varNameCode).name();

        Object value = null;

        if(args.size() == 2){

            value = interpreter.run(args.get(1));

        }

        SymbolTable symbolTable = interpreter.getSymbolTable();

        if( symbolTable instanceof MutableSymbolTable ) {

            if( symbolTable.exists(name)) {

                value = symbolTable.value(name);

            } else {

                ((MutableSymbolTable)symbolTable).setVar(name, value);

            }

        } else {

            throw new RuntimeException("A MutableSymbolTable is required for use VAR function.");

        }

        return value;

    }

    @Override

    public boolean useArgumentsInsteadObjects() {

        return true;

    }

    @Override

    public String toString(Codes args, Formatter<Code> formatter) {

        StringBuilder builder = new StringBuilder();

        builder.append("VAR \"");

        builder.append(Objects.toString(((Code.Identifier)args.get(0)).name()));

        builder.append("\" DEFAULT ");

        builder.append(args.get(1).toString(formatter));

        return builder.toString();

    }

}